Manufacturers of exterior coatings, such as paints and finishes, as well as plastics and other components which tend to degrade under exposure to solar radiation and other weathering effects, often want to know how such products will perform following years of exposure. However, such manufacturers typically require such information in a much shorter time than it would take to expose such materials to weathering effects under normal conditions. Accordingly, accelerated weathering test devices have been developed which accelerate the effects of weathering due to outdoor exposure in a much shorter time so that manufacturers need not actually wait five or ten years in order to determine how their products will hold up after five or ten years of actual outdoor exposure.
Weathering test devices can be categorized into outdoor devices that utilize solar radiation for testing, and indoor devices that generate artificial radiation for testing. Indoor test devices typically include a test chamber, in which test specimens can be exposed to accelerated weathering conditions. These test chambers typically include one or more sources of artificial radiation, such as high intensity plasma lamps, that can direct high intensity radiation toward test specimens that are placed in the test chambers. Additionally, indoor accelerated weathering test devices include a black panel temperature probe that is disposed in the test chamber near the test specimens. The black panel temperature probe typically includes a black painted metallic panel that has a temperature probe mounted thereon. The temperature sensed from the black panel temperature probe typically represents the highest temperature that may be experienced by the test specimens during accelerated weathering tests.
A type of indoor accelerated weathering test device that is commonly used includes a test chamber, in which the test specimens are horizontally arranged on static arrays of specimen trays. These weathering test devices include a generally rectangular test chamber having a ceiling, a floor and a pair of side walls. One or more high intensity plasma lamps, such as Xenon lamps are typically positioned in the ceiling and configured to direct radiation toward the floor of the test chamber. The specimen trays are placed near the floor of the test chamber so that an exposed surface of each specimen receives radiation from the lamps. However, the bottom sides of the test specimens are not exposed to any airflow that may be present in the test chamber. The black panel temperature probe is placed in one of the test specimen trays, and similarly, the bottom side thereof is not exposed to or airflow in the test chamber.
The ASTM 6151 (American Society for Testing and Materials, designation 6151), which is directed to standard practice for exposing nonmetallic materials in accelerated test devices that use laboratory light sources, advises that the back side of the black panel “shall be open to the atmosphere within the exposure chamber.” However, in the above-described indoor accelerated weathering test device, the back side of the black panel is not open to the atmosphere within the exposure chamber. Accordingly, the black panel may experience static and dynamic temperatures that are unrealistic compared to the actual temperatures that are experienced by the test specimens.
Therefore, there exists a need in the art for a black panel that can be placed in the above-described type of indoor accelerated weathering test device such that the backside of the black panel is open to the atmosphere within the exposure chamber of the device.